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The following information is taken from OSS Note 45433

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Customising influences the behaviour of scheduling of the Order.

See the following IMG menu path: Plant Maintenance ->Maintenance Order Management ->PM Orders and service Orders -> Scheduling ->Configure scheduling parameters.

Basic dates: Order header

The basic dates for Orders can be entered directly by the user, determined from the priority of the Order, or determined from the revision.

The basic dates for Orders are used as initial dates for scheduling. They represent the required start or end dates. The start/finish dates can only be moved after scheduling. The scheduling result can move the basic dates for Orders. 

Customising controls whether backwards or forwards scheduling is carried out.

Scheduled dates: Order header

These dates are determined from the Operations of the Order. The earliest scheduled start date of the Operations is used as the start date of the Order. The latest scheduled finish date of the Operations is used as the end date of the Order.     Therefore, the scheduled dates of the Order can only be filled after the scheduling of the Operations.

Scheduling the Operations of the Order

If the Order is scheduled, all Operations of the Order (which are relevant for scheduling) are scheduled.

With the basic dates, (start date if forward scheduled or end date if backward scheduled) the system can determine the dates of the individual Order Operations.

To determine the dates of the various Operations, different information and methods are used. The units of work and the duration affect scheduling. Different information from the Work Centre and Operation also have an influence on scheduling.

Units and scheduling

Based on the units, scheduling is carried out in different ways.

There are the following cases:

Case 1: Unit Weeks or larger.

In this case scheduling of the operating times/Work Centres are not taken into account. The calendar of the Work Centre or the plant is important.

Start-date of the Order:          18/08/97

Duration:                2 Weeks

Calendar: Saturdays and Sunday are not workdays and 01/09/97 is a public holiday.

1 Week is always calculated as 7 days.

1 Month is always calculated as 28 days, and so on

18/08/97 + 7 days = 25/08/1997

If at least 1 workday occurs within these dates, these 7 days (this week) are determined as a scheduled week.

Next week

25/08/97 + 7 days = 01/09/1997

If at least 1 workday occurs within these dates, these 7 days (this week) are determined as a scheduled week.

Since 01/09/1997 is a public holiday, the earliest finish is on 02/09/1997.

Similar calculations are used for the units larger than a week.

Case 2:     Unit Day

In this case scheduling of operating times of the Work Centres is not taken into account. The calendar of the Work Centre or plant is important.

Start date of the Order:          18/08/97

Duration:               3 Days

Calendar:               Saturdays and Sundays are not workdays and 01/09/97 is a public holiday.

08/18/97 + 3 work days = earliest finish

Case 3:     Unit smaller than one day

In Order to calculate the dates of the different Operations, the operating times of the Work Centres are used, in connection with the duration of the respective Operation and the calendar of the Work Centre or the calendar of the plant.

For example:

Forward scheduling is defined.

Start date of the Order:          20/07/96 at 4:00 a.m.

Operation 0010 Duration:          15 Hours.

Work Centre Operation time:      08:00pm to 17:00pm = 8 hrs 7 days shift (1-hour break)

Result:                     Earliest start: 20/07/96 at 8:00am hours can be worked on the first day.

Earliest finish: 21/07/96 at 16:00pm

The following should be noted:

If intervals of available capacity of the Work Centre were to be maintained, they would be used by scheduling.

If a factory calendar in the capacity header were to be maintained, it would be used by scheduling.

If precise break is activated in the header of the Order or in Customising, and intervals of available capacity with shift sequence are also maintained in the Work Centre capacity, then they are used by scheduling.

No capacity is considered during regular Order scheduling.

The capacity scheduling (for PM and PS Orders as of 3.0E) can be performed as separate function. Finite scheduling functions as above will take remaining available capacity into account. See the Work Centre capacity screen for relevant settings to use the capacity scheduling (transaction IR02).  (Transaction IR02).

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2 Comments

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  1. Andrew Barnard

    Thanks for sharing this Pete. It is over 15 years since I wrote this note – and I always intended to expand it to cover the interaction between confirmations and scheduling.

    Since I no longer work for SAP, I can no longer create notes, but I do feel encouraged now to write up the confirmation / scheduling interaction in a blog. And perhaps one day I’ll write up something similar to explain the virtually unexplainable – how the planning table works!

    Cheers

    Andrew

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